class LoginFormView(View):
    form_class = LoginForm
    template_name = 'app_name/login_form.html'

    def get(self, request):
        form = self.form_class(None)

        return render(request, self.template_name, {'form': form})

    def post(self, request):
        form = self.form_class(request.POST)

        if form.is_valid():
            username = form.data['username']
            password = form.data['password']

            user = authenticate(username=username, password=password)

            if user is not None:

                if user.is_active:

                    login(request, user)
                    return redirect('app_name:index')

                else:

                    print("The password is valid, but the account has been disabled!")

            else:
                # Add error message here >
                messages.add_message(request, messages.ERROR, 'Check your data twice.')

        return render(request, self.template_name, {'form': form})